If I am unable to enter into a state of Ihram from the Miqat, and instead enter into Ihram from Makkah to perform the obligatory Hajj, is a sacrifice (Hady) incumbent upon me? And is one such sacrifice sufficient for more than one of the prohibitions of Ihram?

There is no harm in working during Hajj, but one must enter into ihram from the miqat. Whoever passes it without entering into ihram must return to it to enter into ihram from there. Otherwise, a dam (sacrifice) is required, to be slaughtered for the poor of the Haram. This dam does not suffice for another obligation, such as spending the night in Mina, nor for the prohibited acts of ihram. Whoever enters into ihram and then commits a prohibited act, such as wearing tailored clothes, is obligated to pay a fidyah (expiation): fasting for three days, or feeding six needy persons, or slaughtering a sheep. If the same prohibited act is repeated before the fidyah is paid, the fidyah is not repeated. However, if it is repeated after the fidyah is paid, or another prohibited act is committed, another fidyah becomes obligatory. It is advisable to learn the rulings of Hajj, its obligations, and its prohibitions before traveling.